The Downslope is described by The Wrap as a "cautionary, anti-war tale". The story follows a series of Civil War battles in the Shenandoah Valley between Union General George Armstrong Custer and Confederate Colonel John Singleton Mosby, known as the Gray Ghost for his stealth and elusiveness. His cavalrymen, Mosby's Rangers, continually outsmarted the much larger enemy forces in a sequence of raids, which enraged Custer and eventually created a fierce cycle of revenge between the two men.

Stanley Kubrick wrote the screenplay between the release of 1953's Fear and Desire and 1957's Paths of Glory, developing the story with Civil War historian Shelby Foote. The filmmker spent years working on the story, creating maps and extensive notes on how to shoot the war movie. The Downslope will expand on his original story and head West, following Americans settling in the new frontier after the war. Here's what producer Lauren Selig had to say in a statement.

"We've been given the unique privilege to produce a Stanley Kubrick script no one has had the opportunity to make. The first installment of the planned trilogy, written by Kubrick, is an engrossing story illustrating a crucial moment in history toward the end of the American Civil War."

Philip Hobbs and Steve Lanning also offered a joint statement.

"A Stanley Kubrick script deserves a singular director, especially one so gifted working with talented actors. We are thrilled to be collaborating with Marc on this very unique and special project."

"I am indebted to Stanley Kubrick and his visionary films. It is an honor and a huge responsibility to take on this project, and we're thankful to his family for their support. This is a powerful work, an epic story, with its psychological landscape of brother pitted against brother, and friend against friend. We believe it will be an incredibly interesting trilogy, and a great experience sharing our mutual passion of Kubrick's vision."

"I had the rare opportunity to pour over Stanley Kubrick's handwritten notes on this script, which consist of literally hundreds of meticulous and beautifully drawn maps, sketches and journal entries. The level of passion and insight that he had for this intense period of American history is both inspiring and astounding."